Yeah!
Thats the Information that i want 😀 Thanks.
And sorry for my English or Grammatics, i'm not a English man 😁
It's best to use one PSU for both - is right, also to provide some more Power i can add a Aux AT Power to the ISA Backplane and cut all the 4 Power Lines (+5V/+12V/-5V/-12V) out from the first ISA Bracket from Main ISA Mainboard (the Bracket with the Flat Cables) so no Voltages going into the ISA Backplane and can use a secondary AT Power Supply 😁
Because:
I plan to extend my 8 Bit ISA Bus from my Schneider Euro PC II (XT Class Computer) and in the Future i use then a Backplane with an Aux AT Power Source and cut the Power Lines out from the ISA Bracket so no Voltages going into the little XT Class Computer and destroy somethings 😀
Some Off Topic about Power Lines 😊 :
I had a very strange Issue with that Euro PC II and a 8 Bit SCSI Controller (Future Domain 950). When i using a external SCSI Harddisk with his external 12V/5V Power Jack and connect this HDD to my SCSI Controller via the default 50 Pin SCSI Cable so also my Euro PC II is powered on (!) with the Power Switch OFF and no Power from my 18V Power-Brick for the Euro PC II.
Thad was totally crazy, it boots and works ! I found a TE Jumper on the Future Domain 950 Controller that was closed. I think this TE Jumper means like Termination Power and i think:
The SCSI Card provide 5V+ to the ISA Bus (!) and powered this System. I was shocked that a little tiny SCSI Card can power up the System and look at the Traces from the SCSI Card, its so very very tiny and, ... I shutdown my external HDD at about 3 Secs and also the Euro PC II get shutdown 😁 😁 😁 ...
When i set the Jumper TE to disable, so my Euro PC II don't boot and has no power at all, ... CRAZY !!! What the Hell 😕 😀
This was very very confused because the SCSI Card "pulls" 5V Power from the SCSI Cable and also powered the ISA Bus with +5V BUT why my System is booting and starting with that ugly TE Jumper ON only with +5Volts ? The System needs +5V -5V +12V and -12V .....
But still my Euro PC II runs fine and the SCSI Card also 😀 So i had a little problem i thinking, when i use a external Passive ISA Backplane with an external AT Power Supply it also powers my Euro PC II System because all needing Voltages are on the 8 Bit ISA Bus, ... or my 8 Bit SCSI Card has a crazy Layout-Bug, STRANGE 😀
Greetings